Background: We evaluated the mortality due to nosocomial bloodstream infection (BSI) and necrotizing enterocolitis (NEC) in very low birth weight (VLBW) infants in 229 neonatal departments participating in the German national neonatal infection surveillance system between 2000 and 2011.
Methods: For each infection type, we conducted a retrospective cohort study and a case-control study. In the cohort studies, the mortality risk due to BSI and/or NEC was estimated by calculating adjusted hazard ratios (AHRs) with 95% confidence intervals (CIs) using Cox proportional hazard regression with time the dependent variable infection. In the matched case-control studies, the attributable mortality was calculated.
Results: A total of 43,116 VLBW infants, of which 6911 patients had at least 1 BSI and 1271 patients had at least 1 NEC, were analyzed. Overall mortality was 6.6%. Patients with at least 1 BSI had a mortality of 5.6%, and patients with at least 1 NEC had a mortality of 19.2%. The cohort studies revealed that BSI (AHR=1.83; 95% CI: 1.61-2.08) and NEC (AHR=6.35; 95% CI: 5.47-7.37) are independently associated with increased mortality. In the case-control study for BSI, 5187 (75.1%) patients with BSI were matched. Attributable mortality was 1.4% (95% CI: 0.7-2.2). In the case-control study for NEC, 1092 (85.9%) patients with NEC were matched. Attributable mortality was 14.7% (95% CI: 12.2-17.1).
Conclusions: Nosocomial BSI and NEC increased mortality in VLBW infants. BSI, however, was associated with a relatively small attributable mortality of 1.4%, whereas NEC had a high attributable mortality of 14.7%.